1. Field of the Invention
The present invention relates to the field of turbomachines, and in particular to a compressor having a rotor.
2. Brief Description of the Related Art
High-pressure compressors, as are used in particular for compression of the combustion air in gas turbines, include a multistage blade system, which includes rotor blades and stator blades arranged alternately in the axial direction. The rotor blades are mounted on the rotor, which is mounted such that it can rotate. The stator blades are arranged between adjacent rotor blade rims on the inner housing of the compressor.
The air which flows through the annular channel in the compressor formed between the rotor and the inner housing and which is compressed in the process is heated as a result of being compressed. In order to protect the rotor and the inner housing against being thermally overloaded by the heated air, thermal barrier elements are frequently arranged between adjacent rotor blade and stator blade rims, and form a circumferential protective ring (see, for example, DE-A 1-198 08 740). Since the thermal barrier segments are in each case opposite the blade tips of the rotor blades and stator blades, and abut against them, they are a significant factor in the setting of the blade clearance. In order to prevent direct contact between the blade tips and the thermal barrier segments, cutting tools are arranged between the thermal barrier segments, which project by a specific amount beyond the thermal barrier segments and at the same time prevent the thermal barrier segments from being moved in the circumferential direction. However, a rotor design such as this is highly complex to manufacture and assemble.
One known embodiment of the thermal barrier segments on the rotor side, that is to say those which are opposite the stator blades, is described in DE-A-1-196 15 549, and is also illustrated in FIG. 1 of the present application. The known thermal barrier segments 10 are in the form of shell-shaped circular ring segments which have a smooth outer surface 11, with two segment feet 12, which extend parallel in the circumferential direction, and have a hook-shaped cross section, being integrally formed on its lower face. In order to secure the thermal barrier segments 10, a circumferential groove with two hooks which extend over the entire circumference is provided between adjacent rotor blade rims in the rotor, behind which hooks the segment feet of the thermal barrier segments are hooked in. Each of the thermal barrier segments is secured against movement in the circumferential direction by means of a securing pin (FIG. 3 and claim 4 of DE-A-1-196 15 549). In this case as well, the method in which each thermal barrier segment is secured in the circumferential direction involves considerable complexity, because the corresponding holes must be incorporated in the rotor and in the thermal barrier segments, and the securing pins must be installed. Furthermore, in this case, no precautions are taken to set a specific clearance between the thermal barrier segments and the blade tips.